The present invention concerns naphtho and dihydrobenzo-thiophene derivatives, which are active as antitumor agents and in inhibiting cellular mitosis, along with pharmaceutical formulations containing the same.
Many naturally occurring substituted anthraquinone and naphthoquinones possess cytotoxic antileukemic activities (Zee-Cheng P. et al., J. Med. Chem. 1979, 22, 501-505; Chang, P., Lee, K. H. Phytochemistry. 1984, 23, 1733-1736; T. Hayashi, F. Smith, and K. H. Lee, K. H. J. Med. Chem. 1987, 30, 2005-2008). In addition, the natural furanonaphthoquinones 1 and 2 and their synthetic analog 3 (see figures below) show potent cytotoxicity against KB cells with ED50 values of 1.0, 2.0, and 0.3 xcexcg/mL, respectively (Rao, M. M.; Kingston, D. G. I. J. Nat. Prod. 1982, 45, 600-604).
The unsubstituted thiophene derivative naphtho[2,3-b]thiophene-4,9-dione (4) also was found to be cytotoxic against KB cells with an ED50 value of 1.4 xcexcg/mL (Goncalves, R.; Brown, E. V. J. Org. Chem. 1952, 17, 698-704; Weinmayr, V. U.S. Pat. No. 2,497,334 1950; Weinmayr, V. J. Am. Chem. Soc. 1952, 74, 4353-4357; Carruthers, W.; Douglas, A. G.; Hill, J. J. Chem. Soc. 1962, 704-708; Carruthers, W. J. Chem. Soc. 1963, 4477-4483; Tagawa, H.; Ueno, K. Chem. Pharm. Bull. 1978, 26, 1384-1393; Huang, L. J.; Kuo, S. C.; Perng, C. Y.; Chao, Y. H.; Wu, T. S.; McPhail, A. T.; Cheng, H. H.; Lee, K. H. Bioorg and Med. Chem. Letters, submitted.) Introduction of a lipophilic acetyl group gave 2-acetyl naphtho[2,3-b]thiophene-4,9-dione (5) with enhanced cytotoxicity (ED50=0.4 xcexcg/mL)(Huang, L. J.; Kuo, S. C.; Perng, C. Y.; Chao, Y. H.; Wu, T. S.; McPhail, A. T.; Cheng, H. H.; Lee, K. H. Bioorg and Med. Chem. Letters, submitted).
A first aspect of the present invention is a compound selected from the group consisting of compounds of Formula I and compounds of Formula II: 
wherein:
R1, R2, R3 and R4 are each independently selected from the group consisting of:
hydrogen, alkyl, carboxy, alkoxy, hydroxyalkyl, alkylcarbonyl; alkylcarbonyloxy; alkyl substituted with alkylcarbonyloxy, thiophenylcarbonyl; nitro and cyano;
thiophenyl and thiophenylthiophenyl, each of which may be unsubstituted or substituted with alkyl, carboxy, alkoxy, hydroxyalkyl, alkylcarbonyl; alkylcarbonyloxy; alkyl substituted with alkylcarbonyloxy, nitro or cyano;
subject to the proviso that at least one of R1, R2, R3 and R4 is not hydrogen;
A1 and A2 are each selected from the group consisting of: xe2x95x90O, alkyl, alkoxy, and alkylcarbonyloxy;
and the pharmaceutically acceptable salts thereof.
Note that, When A1 and A2 are xe2x95x90O, the center ring has only two, and not three, double bonds, as shown in Formula Ia and IIa below.
In a preferred embodiment of the foregoing, at two or (most preferably) three of R1, R2, R3 and R4 are hydrogen.
A second aspect of the present invention is a compound according to Formula III: 
wherein:
R1, R2, R3, R4, R5 and R6 are each independently selected from the group consisting of:
hydrogen, alkyl, carboxy, alkoxy, hydroxyalkyl, alkylcarbonyl, alkylcarbonyloxy, alkyl substituted with alkylcarbonyloxy, thiophenylcarbonyl; nitro and cyano;
thiophenyl and thiophenylthiophenyl, each of which may be unsubstituted or substituted with alkyl, carboxy, alkoxy, hydroxyalkyl, alkylcarbonyl, alkylcarbonyloxy, alkyl substituted with alkylcarbonyloxy, nitro or cyano;
subject to the proviso that at least one of R1, R2, R3 and R4 is not hydrogen;
and the pharmaceutically acceptable salts thereof.
A further aspect of the present invention is a composition comprising an effective antitumor amount of a compound of Formula I, II or III above, or a pharmaceutically acceptable salt thereof, in a pharmaceutically acceptable carrier.
A further aspect of the present invention is a method for treating a tumor, the method comprising administering to a subject in need of treatment a compound of Formula I, II or III above, or a pharmaceutically acceptable salt thereof, in an amount effective to treat said tumor.
A still further aspect of the present invention is a method for inhibiting cellular mitosis, said method comprising contacting a cell with a compound of Formula I, II or III above, or a pharmaceutically acceptable salt thereof, in an amount effective to inhibit cellular mitosis.
A still further aspect of the present invention is the use of a compound of Formula I, II or III above, or a pharmaceutically acceptable salt thereof, for the preparation of a medicament for carrying out the methods described above.
The term xe2x80x9calkylxe2x80x9d as used herein, inidividually or as a portion of another substituent term such as xe2x80x9calkoxyxe2x80x9d, refers to C1 to C4 alkyl, which may be linear or branched, and saturated or unsaturated. Preferably, the alkyl is saturated, and preferably the alkyl is linear.
The term xe2x80x9chalogenxe2x80x9d or xe2x80x9chaloxe2x80x9d as used herein refers to fluorine, chlorine, bromine, iodine, etc., or fluoro, chloro, bromo, iodo, etc., respectively.
Compounds of the present invention can be made in accordance with known techniques, or variations thereof which will be apparent to those skilled in the art in given the Examples set forth below.
Specific examples of compounds of Formula I and II are compounds of Formula Ia and compounds of Formula IIa: 
wherein:
R1, R2, R3 and R4 are each independently selected from the group consisting of:
hydrogen, alkyl, carboxy, alkoxy, hydroxyalkyl, alkylcarbonyl, alkylcarbonyloxy, alkyl substituted with alkylcarbonyloxy, thiophenylcarbonyl; nitro and cyano;
thiophenyl and thiophenylthiophenyl, each of which may be unsubstituted or substituted with alkyl, carboxy, alkoxy, hydroxyalkyl, alkylcarbonyl, alkylcarbonyloxy, alkyl substituted with alkylcarbonyloxy, nitro or cyano;
subject to the proviso that at least one of R1, R2, R3 and R4 is not hydrogen;
and the pharmaceutically acceptable salts thereof.
Additional examples of compounds of Formulas I and II are compounds of Formula Ib and compounds of Formula IIb: 
wherein:
R1, R2, R3 and R4 are each independently selected from the group consisting of:
hydrogen, alkyl, carboxy, alkoxy, hydroxyalkyl, alkylcarbonyl, alkylcarbonyloxy; alkyl substituted with alkylcarbonyloxy, thiophenylcarbonyl, nitro and cyano;
thiophenyl and thiophenylthiophenyl, each of which may be unsubstituted or substituted with alkyl, carboxy, alkoxy, hydroxyalkyl, alkylcarbonyl, alkylcarbonyloxy, alkyl substituted with alkylcarbonyloxy, nitro or cyano;
subject to the proviso that at least one of R1, R2, R3 and R4 is not hydrogen;
A1 and A2 are each selected from the group consisting of alkyl, alkoxy, and alkylcarbonyloxy;
and the pharmaceutically acceptable salts thereof.
Thiophenyl and thiophenylthiophenyl substituents that may be used to carry out the present invention include those having the structures: 
where R7 is the same as given in connection with R1 through R4 above.
Compounds illustrative of Formulas I and II above (along with the reference numbers assigned to these compounds in Examples 1-13 below), are:
2-Acetyl-4,8-dihydrobenzo[1,2-b:4,5-bxe2x80x2]dithiophene-4,8-dione (9);
2-(1xe2x80x2-Hydroxyethyl)-4,8-dihydrobenzo[1,2-b:4,5-bxe2x80x2]dithiophene-4,8-dione (10);
2-(1xe2x80x2-Acetoxyethyl)-4,8-dihydrobenzo[1,2-b:4,5-bxe2x80x2]dithiophene-4,8-dione (11);
2,7-Diacetyl-4,8-dihydrobenzo[1,2-b:4,5-bxe2x80x2]dithiophene-4,8-dione (13);
2,7-Bis(1xe2x80x2-hydroxyethyl)-4,8-dihydrobenzo[1,2-b:4,5-bxe2x80x2]dithiophene-4,8-dione (14);
2,7-Bis(1xe2x80x2-acetoxyethyl)-4,8-dihydrobenzo[1,2-b:4,5-bxe2x80x2]dithiophene-4,8-dione (15);
2-Acetyl-4,8-dihydrobenzo[1,2-b:5,4-bxe2x80x2]dithiophene-4,8-dione(19);
2-(1xe2x80x2-Hydroxyethyl)-4,8-dihydrobenzo[1,2-b:5,4-bxe2x80x2]dithiophene-4,8-dione (20);
2-(1xe2x80x2-Acetoxyethyl)-4,8-dihydrobenzo[1,2-b:5,4-bxe2x80x2]dithiophene-4,8-dione (21);
2,7-Diacetyl-4,8-dihydrobenzo[1,2-b:5,4-bxe2x80x2]dithiophene-4,8-dione (23);
2,7-Bis(1xe2x80x2-hydroxyethyl)-4,8-dihydrobenzo[1,2-b:5,4-bxe2x80x2]dithiophene-4,8-dione (24);
2,7-Bis(1xe2x80x2-acetoxyethyl)-4,8-dihydrobenzo[1,2-b:5,4-bxe2x80x2]dithiophene-4,8-dione (25).
Compounds of Formula III (along with the numbers assigned to these compounds in Examples 14-16 below) are as follows:
2-Acetyl-naphtho[2,3-b]thiophene-4,9-dione (5);
3-Acetyl-naphtho[2,3-b]thiophene-4,9-dione (6);
7-Acetyl-naphtho[2,3-b]thiophene-4,9-dione (7);
2,7-Diacetyl-naphtho[2,3-b]thiophene-4,9-dione (9);
3,7-Diacetyl naphtho[2,3-b]thiophene-4,9-dione (10).
Additional compounds illustrative of Formulas I and II above are as follows:
The compounds of Formula I, II and III (hereinafter referred to along with their pharmaceutically acceptable salts as xe2x80x9cactive compoundsxe2x80x9d) are useful as pharmaceutically active agents. The active compounds may be formulated for administration for the treatment of a variety of conditions. In the manufacture of a pharmaceutical formulation according to the invention, the actove compounds including the physiologically acceptable salts thereof, or the acid derivatives of either thereof are typically admixed with, inter alia, an acceptable carrier. The carrier must, of course, be acceptable in the sense of being compatible with any other ingredients in the formulation and must not be deleterious to the patient. The carrier may be a solid or a liquid, or both, and is preferably formulated with the compound as a unit-dose formulation, for example, a tablet, which may contain from 0.5% to 95% by weight of the active compound. One or more active compounds may be incorporated in the formulations of the invention, which may be prepared by any of the well known techniques of pharmacy consisting essentially of admixing the components, optionally including one or more accessory ingredients.
The formulations of the invention include those suitable for oral, rectal, topical, buccal (e.g., sub-lingual), parenteral (e.g., subcutaneous, intramuscular, intradermal, or intravenous) and transdermal administration, although the most suitable route in any given case will depend on the nature and severity of the condition being treated and on the nature of the particular active compound which is being used.
Formulations suitable for oral administration may be presented in discrete units, such as capsules, cachets, lozenges, or tablets, each containing a predetermined amount of the active compound; as a powder or granules; as a solution or a suspension in an aqueous or non-aqueous liquid; or as an oil-in-water or water-in-oil emulsion. Such formulations may be prepared by any suitable method of pharmacy which includes the step of bringing into association the active compound and a suitable carrier (which may contain one or more accessory ingredients as noted above). In general, the formulations of the invention are prepared by uniformly and intimately admixing the active compound with a liquid or finely divided solid carrier, or both, and then, if necessary, shaping the resulting mixture. For example, a tablet may be prepared by compressing or molding a powder or granules containing the active compound, optionally with one or more accessory ingredients. Compressed tablets may be prepared by compressing, in a suitable machine, the compound in a free-flowing form, such as a powder or granules optionally mixed with a binder, lubricant, inert diluent, and/or surface active/dispersing agent(s). Molded tablets may be made by molding, in a suitable machine, the powdered compound moistened with an inert liquid binder.
Formulations suitable for buccal (sub-lingual) administration include lozenges comprising the active compound in a flavoured base, usually sucrose and acacia or tragacanth; and pastilles comprising the compound in an inert base such as gelatin and glycerin or sucrose and acacia.
Formulations of the present invention suitable for parenteral administration conveniently comprise sterile aqueous preparations of the active compound, which preparations are preferably isotonic with the blood of the intended recipient. These preparations may be administered by means of subcutaneous, intravenous, intramuscular, or intradermal injection. Such preparations may conveniently be prepared by admixing the compound with water or a glycine buffer and rendering the resulting solution sterile and isotonic with the blood.
Formulations suitable for rectal administration are preferably presented as unit dose suppositories. These may be prepared by admixing the active compound with one or more conventional solid carriers, for example, cocoa butter, and then shaping the resulting mixture.
Formulations suitable for topical application to the skin preferably take the form of an ointment, cream, lotion, paste, gel, spray, aerosol, or oil. Carriers which may be used include vaseline, lanoline, polyethylene glycols, alcohols, transdermal enhancers, and combinations of two or more thereof.
Formulations suitable for transdermal administration may be presented as discrete patches adapted to remain in intimate contact with the epidermis of the recipient for a prolonged period of time. Formulations suitable for transdermal administration may also be delivered by iontophoresis (see, for example, Pharmaceutical Research 3 (6):318 (1986)) and typically take the form of an optionally buffered aqueous solution of the active compound. Suitable formulations comprise citrate or bistris buffer (pH 6) or ethanol/water and contain from 0.1 to 0.2M active ingredient.
The active compounds inhibit tubulin polymerization and have antimitotic activity. Such compounds are useful for the treatment of conditions including psoriasis, gout, papiloma, warts, and various tumors including but not limited to non-small cell lung cancer, colon cancer, central nervous system cancers, melanoma, ovarian cancer, prostate cancer and breast cancer.
Subjects to be treated by the methods of the present invention are typically human subjects although the methods of the present invention may be useful with any suitable subjects known to those skilled in the art, and particularly mammalian subjects including, in addition to humans, horses, cows, dogs, rabbits, fowl, sheep, and the like, for veterinary purposes. As noted above, the present invention provides pharmaceutical formulations comprising the active compounds (including the pharmaceutically acceptable salts thereof), in pharmaceutically acceptable carriers for oral, rectal, topical, buccal, parenteral, intramuscular, intradermal, or intravenous, and transdermal administration.
The therapeutically effective dosage of any specific compound, the use of which is in the scope of present invention, will vary somewhat from compound to compound, patient to patient, and will depend upon the condition of the patient and the route of delivery. As a general proposition, a dosage from about 0.1 to about 50 mg/kg will have therapeutic efficacy, with still higher dosages potentially being employed for oral and/or aerosol administration. Toxicity concerns at the higher level may restrict intravenous dosages to a lower level such as up to about 10 mg/kg, all weights being calculated based upon the weight of the active base, including the cases where a salt is employed. Typically a dosage from about 0.5 mg/kg to about 5 mg/kg will be employed for intravenous or intramuscular administration. A dosage from about 10 mg/kg to about 50 mg/kg may be employed for oral administration.